1. Field of the Invention
The present invention relates to solid rocket propellants and, more particularly, to metal containing propellants having improved burning characteristics and burning rates.
2. Description of the Prior Art
Composite solid rocket propellants based on a dispersion of solid oxidizer in an organic binder have been formulated with a high content of combustible metal such as aluminum to maximize specific impulse and reduce combustion instability by forming solid particulates in the exhaust gases. However, these metal oxide particulates are found to form aluminum oxide slag which deposits and accumulates in the nozzle throat leading to decrease in effective throat area and finally to nozzle blockage, especially in the laboratory scale end burner units utilized in developmental programs.
Instability in solid propellant rocket motors continues to be a major problem in most, if not all, motor developmental programs. The term: "L* Instability" denotes various phenomena: chuffing, or intermittent combustion, bulk mode instability involving periodic oscillations superimposed on a mean chamber pressure, neither of which may have a constant value as time varies, and several combinations of these phenomena, including the depressurization rate (dp/dt) extinguishment. The L* mode of combustion instability appears to be, by far, the simplest of unstable operations. On account of this simplicity, and its intrinsic interest, L* instability as determined in standardized stainless steel L* motors with interchangeable stainless steel nozzles is currently the subject of extensive experimental effort. The troublesome blockage of L* or L-star motor small metal nozzles by metal oxide slags has interfered with testing of metallized propellants for L-star instability characteristics.